Pushrod for a Valve Gear of an Internal Combustion Engine

ABSTRACT

The invention concerns a pushrod for a valve gear of an internal combustion engine. The invention furthermore concerns a valve gear and a motor vehicle, in particular a truck, with such a pushrod. The pushrod (1) is distinguished in that to increase the bending resistance, a shank (2) of the pushrod (1) has a rib structure (3).

The invention concerns a pushrod for a valve gear of an internalcombustion engine.

The invention furthermore concerns a valve gear of an internalcombustion engine comprising such a pushrod, in particular a valve gearfor an internal combustion engine with side- or bottom-mounted camshaft.The invention furthermore concerns such an internal combustion engine,e.g. an engine in particular for a vehicle, e.g. a motor vehicle, atruck, a water vessel, a rail vehicle, or an internal combustion enginefor power generation, comprising such a pushrod.

The invention furthermore concerns a vehicle, in particular a motorvehicle, e.g. a truck, a water vessel, a rail vehicle, with a pushrod ora valve gear as described in this document.

A pushrod for a valve gear forms the transmission element in the drivemechanism from the camshaft to the valves. Colloquially, the term tappetpushrod is often used for the pushrod. The pushrod in an internalcombustion engine is part of the valve gear in engines, in particularengines with side- or bottom-mounted camshaft. Known pushrods consistsof a cylindrical shank with ball heads or ball sockets on its ends.

To increase the bending stiffness, it is known from the prior art not toconfigure the shank of the pushrod so as to be tubular or cylindrical,but to make a portion of the shank more resistant to bending with adouble conical form in a middle region of the pushrod, as described forexample from AT 005 130 U1, U.S. Pat. No. 4,850,315 A or U.S. Pat. No.5,027,763 A. Thus AT 005 130 U1 discloses a pushrod with a region ofmaximum cross-section arranged preferably centrally between the ends ofthe pushrod, wherein the pushrod consists of a first and a secondsubstantially hollow rod part; these rod parts each have a maximumcross-section in the region of an open end face, wherein the rod partsare connected together inseparably at their open end faces (2 b, 3 b).

It is an object of the invention to refine the known prior art in orderto provide a pushrod with a high bending stiffness which can be usedflexibly in valve gear with restricted installation space.

This object is achieved by a pushrod with the features of theindependent claim. Advantageous embodiments and applications of theinvention are the subject of the dependent claims, and are explained inmore detail in the description below with partial reference to thefigures.

According to general aspects of the invention, a pushrod is provided, inparticular for a valve gear of an internal combustion engine, the shankof which has a rib structure.

The ribs, i.e. the provision of a rib structure to increase the bendingstrength of a defined region of the pushrod, increases the bendingresistance of the pushrod in comparison with a cylindrical design of thepushrod shank. In addition, a weight reduction can be achieved, whichalso improves the valve drive dynamics. A further advantage of thispushrod design is the use of the pushrod even in regions in whichinstallation space is critical, thanks to the tapering of the pushrod inregions which are less susceptible to bending. In particular, incomparison with the double conical or “swollen” design of the shankknown from the prior art, the rib structure offers, with equally goodbending strength, greater flexibility in adapting the dimensions of thepushrod to the prevailing space requirement in regions in whichinstallation space is critical. Depending on the installation spaceavailable, for example the length of the rib structure, the numberand/or size of the ribs of the rib structure, may be adapted. Thespacing of the start and end of the ribs may thus suitably be selecteddepending on the installation space in the engine.

According to a particularly preferred embodiment, the rib structure hasseveral radially protruding ribs extending in the longitunal directionof the shank. In other words, several ribs running at leastapproximately axially parallel to the shank centre axis may be provided.The ribs may protrude to the same extent or to different extents in theradial direction. An advantageous variant provides that the ribsprotrude to the same extent in the radial direction.

The number of ribs of the rib structure may lie in the range from threeto twelve, further preferably in the range from four to eight.

The rib structure is arranged in a region of the shank between the endsof the pushrod. A preferred embodiment provides that the rib structureis arranged in a middle region of the shank. Here, the rib structure maybe arranged only in the middle region, so that no rib structure isarranged on the two opposing ends of the pushrod. A possible embodimenthere provides that the rib structure is arranged only in a middle regionof the shank which corresponds at most to ⅔, further preferably at mostto half of a length of the shank.

In this way, the pushrod can be configured tapering at the ends of thepushrod in a region which is less susceptible to bending. This isfurthermore advantageous for arrangement in a region, in whichinstallation space is critical, between the pushrod and the cylinderhead of the internal combustion engine.

According to a further aspect, the rib structure may be formedintegrally with the shank, which is advantageous for stability reasonsand with respect to production of the pushrod.

According to a further aspect, a thickness of at least one rib of therib structure diminishes in the radial direction away from the shank atleast in portions.

According to a further aspect, a rib of the rib structure may incross-section have the form of a wedge or rectangle. Furthermore, a ribof the rib structure may have radially rounded corners at the radiallyouter edge of the rib.

According to a further aspect, an outside of the ribs of the ribstructure may in cross-section have the form of a circle portion withthe radius of the shank in the region of the rib structure. The radiusof the shank in this region constitutes the height of the ribs in thisregion. Furthermore, the two edges which extend inward from an outsideof the ribs may be bevelled, widening towards the inside.

The ends of the shank of the pushrod may be provided with a ball head ora ball socket. The pushrod may be made of conventional structural steelor tool steel. The pushrod and/or the pushrod shank may be produced as adrawn tube with ribs, wherein the shank is freely turned at its twoopposing ends. The pushrod and/or the pushrod shank may be produced as adrawn round bar with ribs and freely turned at the ends of the shank.The pushrod and/or the shank may furthermore be forged or formed asround material.

The rib structure may run out straight or be “swollen” on the shank. Therib structure may be configured with or without chamfer.

The invention furthermore concerns a valve gear of an internalcombustion engine comprising a pushrod as described in this document, inparticular a valve gear for an internal combustion engine with side- orbottom-mounted camshaft. The invention furthermore concerns such aninternal combustion engine, e.g. an engine in particular for a vehicle,e.g. a motor vehicle, a truck, a water vessel, a rail vehicle, or forpower generation, comprising a pushrod as described in this document.

The invention furthermore comprises a vehicle, in particular a motorvehicle e.g. a truck, a water vessel or a rail vehicle, with a pushrodor a valve gear as described in this document.

The preferred embodiments and features of the invention described abovemay be combined with each other arbitrarily. Further details andadvantages of the invention are described below with reference to theenclosed drawings. The drawings show:

FIG. 1 a pushrod according to an embodiment of the invention; and

FIG. 2 a cross-section along line B-B in FIG. 1.

The same elements or those with equivalent function are designated withthe same reference signs in all figures.

FIG. 1 shows a pushrod 1 according to an embodiment of the invention.

The pushrod 1 may be used in a valve gear for an internal combustionengine, and here form the transmission element in the drive mechanismfrom the side- or bottom-mounted camshaft to the gas exchange valves.Colloquially, the term tappet pushrod is often used for the pushrod.

The pushrod 1 comprises a shank 2, at the ends of which a ball head 6 ora ball socket 5 are provided.

In the embodiment variant shown in FIG. 1, a middle region 2 b of theshank 2 has a rib structure 3. The rib structure 3 is formed by severalradially protruding ribs 4 extending in the longitudinal direction L ofthe shank 2, wherein the rib structure 3 is formed integrally with theshank 2.

The longitudinal direction here corresponds to the longitudinal axis Lof the shank 2. A radial direction is perpendicular to the longitudinalaxis L. The two opposing end regions 2 a of the shank 2, which areconfigured cylindrically, adjoin the middle region 2 b of the shank 2.

The rib structure 3 is also shown in FIG. 2 which depicts across-section along line B-B in FIG. 1.

In the present case, the rib structure has four ribs 4 which run in thelongitudinal direction parallel to the longitudinal axis L of the shankand protrude to the same extent in the radial direction. Merely as anexample, a thickness of the ribs 4 of the rib structure 3 diminishes inthe radial direction R away from the shank at least in portions. Theribs 4 have in cross-section the form of a wedge or rectangle withrounded corners on the radially outer edge 4 a. The two edges whichextend inward from an outside 4 a of a rib 4 are bevelled, wideningtowards the inside.

Although the invention has been described with reference to specificexemplary embodiments, it is evident to a person skilled in the art thatvarious changes may be made and equivalents used as substitutes withoutleaving the scope of the invention. Consequently, the invention is notrestricted to the exemplary embodiments disclosed but comprises allexemplary embodiments which fall within the scope of the enclosedclaims. In particular, the invention also claims protection for thesubject and features of the subclaims independently of the claims towhich they refer.

LIST OF REFERENCE SIGNS

1 Pushrod

2 Shank

2 a Outer portion of shank

2 b Middle portion of shank

3 Rib structure

4 Rib

5 End region formed as ball cup

6 End region formed as ball

L Longitudinal axis

1. A pushrod for a valve gear for an internal combustion engine,characterized in that a shank of the pushrod has a rib structure.
 2. Thepushrod according to claim 1, wherein the rib structure has a pluralityof radially protruding ribs extending in the longitudinal direction ofthe shank.
 3. The pushrod according to claim 2, wherein a number of ribsof the rib structure lies in the range from three to twelve.
 4. Thepushrod according to claim 2, wherein a number of ribs of the ribstructure lies in the range from four to eight.
 5. The pushrod accordingto claim 1, wherein the rib structure is arranged in a middle region ofthe shank.
 6. The pushrod according to claim 5, wherein the ribstructure is arranged only in a middle region of the shank whichcorresponds at most to ⅔ of a length of the shank.
 7. The pushrodaccording to claim 5, wherein the rib structure is arranged only in amiddle region of the shank which corresponds at most to half of a lengthof the shank.
 8. The pushrod according to claim 1, wherein the ribstructure is formed integrally with the shank.
 9. The pushrod accordingto claim 2, wherein a thickness of at least one rib of the rib structurediminishes in the radial direction away from the shank at least inportions.
 10. The pushrod according to claim 1, wherein a) a rib of therib structure has in cross-section the form of a wedge or rectangle,preferably with rounded corners at the radially outer edge; and/or b) aradially outer edge of the ribs of the rib structure has incross-section the form of a circle portion with the radius of the shankin the region of the rib structure.
 11. A valve gear of an internalcombustion engine, comprising a pushrod, characterized in that a shankof the pushrod has a rib structure.
 12. An internal combustion enginewith a pushrod, characterized in that a shank of the pushrod has a ribstructure.
 13. A vehicle, for example a motor vehicle, in particular atruck, a water vessel, a rail vehicle, with a pushrod, characterized inthat a shank of the pushrod has a rib structure.